I can't get any sound trying to playback previously recorded projects. I can start a new project and record and playback with sound as expected but if I load another project I get no sound on playback. And if I switch back to the newly recorded project same thing, no output. Meters indicate sound playback. I've restarted the ipad (pro 12.9 2017), restarted Auria Pro.

What happens after you unplug and plug your headphones? (Or plug then unplug, depending if you are using headphones or not)
I had some sporadic issues with no output sound in previous AP version that were fixed unpluging/pluging my headphones, maybe this could be something similar.